Power density matching for power amplifiers

ABSTRACT

Circuits and methods related to power amplifiers. In some implementations, a bias circuit includes a reference device connectable to receive a first electrical supply level, the reference device arranged to produce an electrical bias condition using the first electrical supply level, and the reference device connectable to provide the electrical bias condition to an amplifier device connectable to a second electrical supply level. The bias circuit also includes a power density translating circuit connectable between the reference device and the amplifier device, the power density matching circuit provided to substantially set a first power density associated with the reference device and a second power density associated with the amplifier device relative to one another, the first power density being a function of the first electrical supply level and the second power density being a function of the second electrical supply level.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to U.S. Provisional Application No. 62/069,205 filed Oct. 27, 2014, entitled POWER DENSITY MATCHING FOR POWER AMPLIFIERS, the disclosure of which is hereby expressly incorporated by reference herein in its entirety.

BACKGROUND

Field

The present disclosure relates to power amplifiers in radio-frequency applications.

Description of the Related Art

Power amplifiers (PA) are widely used in networks in order to set the transmission power level of an information-bearing signal. For example, PAs are used to set the pulse emission energy of lasers in optical networks. PAs are also included in various wireless network devices—such as base stations and mobile devices—in order to set the transmission power level of a radio-frequency (RF) signal. PAs are also used in local area networks in order to enable wired and wireless connectivity of various devices.

Managing PA operation is important in a mobile device that uses a battery, because the power consumption of the PA often has a substantial impact on battery life. However, satisfying power consumption goals can be detrimental to other goals, such as linearity, which affects signal integrity and error control in data packets.

For example, bias circuitry is often provided to support the gain function of a PA, in addition to establishing the quiescent on-state conditions of PA transistors. Preferably, bias conditions support the PA in providing relatively constant gain, as a function of time, across a duration used to transmit a data packet. According to a first approach, bias circuitry is configured to operate using a lower voltage supply than the PA transistor in order to reduce power consumption.

A second approach includes switching the PA and the bias circuitry from an off-state to an on-state on demand (and then back to the off-state), so that the PA and bias circuitry do not dissipate power when data is not being transmitted. However, PA linearity is adversely affected by combining the first and second approaches. Nonlinear changes in the respective temperatures of the bias circuitry and the PA stem from the different voltage supply levels provided to each, and a switch from an off-state to an on-state. In turn, the power density in the PA does not track the power density in the bias circuitry, which causes a non-linear variation in gain that can be measured as a degradation in error vector magnitude (EVM).

SUMMARY

In accordance with a number of implementations, the present disclosure relates to a bias circuit that includes a reference device connectable to receive a first electrical supply level, the reference device arranged to produce an electrical bias condition using the first electrical supply level, and the reference device connectable to provide the electrical bias condition to an amplifier device connectable to a second electrical supply level. The bias circuit also includes a power density translating circuit connectable between the reference device and the amplifier device, the power density matching circuit provided to substantially set a first power density associated with the reference device and a second power density associated with the amplifier device relative to one another, the first power density being a function of the first electrical supply level and the second power density being a function of the second electrical supply level.

In some implementations, at least one of the reference device and the amplifier device includes one of a BJT, a MOSFET, a HBT, a MESFET, and a GaAsFET.

In some implementations, the first electrical supply level is a first voltage level that is less than a second voltage level corresponding to the second electrical supply level.

In some implementations, the first power density is associated with a first transistor included in the reference device, and the second power density is associated with a second transistor included in the amplifier device.

In some implementations, the power density matching circuit includes a current translator circuit.

In some implementations, the current translator circuit includes a combination of transistors that are each sized relative to one another in order to set a current density in the amplifier relative to a current density in the reference device.

In some implementations, the current translator circuit includes portions of at least two current mirror arrangements of transistors.

In some implementations, the current translator circuit operation is substantially independent of temperature.

In some implementations, the present disclosure relates to a module that includes a packaging substrate configured to receive a plurality of components. The module also includes a reference device connectable to receive a first electrical supply level, the reference device arranged to produce an electrical bias condition using the first electrical supply level, and the reference device connectable to provide the electrical bias condition to an amplifier device connectable to a second electrical supply level, and at least a portion of the reference device is included on the packaging substrate. The module further includes a power density matching circuit connectable between the reference device and the amplifier device, the power density matching circuit provided to substantially set a first power density associated with the reference device and a second power density associated with the amplifier device relative to one another, the first power density being a function of the first electrical supply level and the second power density being a function of the second electrical supply level, and at least a portion of the power density matching circuit is included on the packaging substrate.

In some implementations, the module is a power amplifier (PA) module.

In some implementations, at least a portion of the power density matching circuit is included on a first die.

In some implementations, the first electrical supply level is a first voltage level that is less than a second voltage level corresponding to the second electrical supply level.

In some implementations, the first power density is associated with a first transistor included in the reference device, and the second power density is associated with a second transistor included in the amplifier device.

In some implementations, the power density matching circuit includes a current translator circuit.

In some implementations, the current translator circuit includes a combination of transistors that are each sized relative to one another in order to set a current density in the amplifier relative to a current density in the reference device.

In some implementations, the current translator circuit includes portions of at least two current mirror arrangements of transistors.

According to some teachings, the present disclosure relates to a radio-frequency (RF) device that includes a transceiver configured to process RF signals. The RF device also includes an antenna in communication with the transceiver configured to facilitate transmission of an amplified RF signal and a power amplifier connected to the transceiver and configured to generate the amplified RF signal. The RF device further includes a bias module. The bias module includes a reference device connectable to receive a first electrical supply level, the reference device arranged to produce an electrical bias condition using the first electrical supply level, and the reference device connectable to provide the electrical bias condition to power amplifier connectable to a second electrical supply level. The bias module also includes a power density matching circuit connectable between the reference device and the power amplifier, the power density matching circuit provided to substantially set a first power density associated with the reference device and a second power density associated with the power amplifier relative to one another, the first power density being a function of the first electrical supply level and the second power density being a function of the second electrical supply level.

In some implementations, the RF device includes a wireless device. In some implementations, the wireless device includes at least one of a base station, a repeater, a cellular phone, a smartphone, a computer, a laptop, a tablet computer, and peripheral device.

In some implementations, the power density matching circuit includes a current translator circuit.

In some implementations, the current translator circuit includes a combination of transistors that are each sized relative to one another in order to set a current density in the amplifier relative to a current density in the reference device.

For purposes of summarizing the disclosure, certain aspects, advantages and novel features of the inventions have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the present disclosure can be understood in greater detail, a more particular description may be had by reference to the features of various implementations, some of which are illustrated in the appended drawings. The appended drawings, however, merely illustrate the more pertinent features of the present disclosure and are therefore not to be considered limiting, for the description may admit to other effective features.

FIG. 1 is a simplified block diagram of a power amplifier arrangement in accordance with some implementations.

FIG. 2 is a schematic diagram of a power amplifier arrangement with a power density matching circuit in accordance with some implementations.

FIGS. 3A-3C are schematic diagrams of different integrated circuit implementations of the power density matching circuit of FIG. 2.

FIG. 4 is a schematic diagram of an implementation of a module including the power density matching circuit of FIG. 2.

FIG. 5 is a schematic diagram of an implementation of a wireless device including the power density matching circuit of FIG. 2.

In accordance with common practice the various features illustrated in the drawings may not be drawn to scale. Accordingly, the dimensions of the various features may be arbitrarily expanded or reduced for clarity. In addition, some of the drawings may not depict all of the components of a given system, method or device. Finally, like reference numerals may be used to denote like features throughout the specification and figures.

DETAILED DESCRIPTION OF SOME IMPLEMENTATIONS

The headings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the claimed invention.

Power amplifiers (PA) are widely used in networks in order to set the transmission power level of a data-bearing signal. For example, PAs are used to set the pulse energy of lasers in optical networks. PAs are also included in various wireless network devices—such as base stations and mobile devices—in order to set the power level of a radio-frequency (RF) signal. PAs are also used in local area networks in order to enable wired and wireless connectivity.

Management of PA operation is generally important in a mobile device that uses a battery, because the power consumption of the PA has a substantial impact on battery life. However, power consumption goals often compete with various other goals of PA operation, such as linearity, which affects signal integrity and data error control.

FIG. 1, for example, is a schematic diagram of a power amplifier (PA) operating configuration 100 according to some implementations. While pertinent features are illustrated, those skilled in the art will appreciate from the present disclosure that various other features have not been illustrated for the sake of brevity and so as not to obscure more pertinent aspects of the example implementations disclosed herein. To that end, as a non-limiting example, the PA operating configuration 100 includes a PA 110 and a bias circuit 120.

The bias circuit 120 is coupled to a first voltage supply line (V_(CC1)) 101 in order to receive the first voltage level V_(CC1). The bias circuit 120 includes a reference transistor (Q_(ref)) 125. While the reference transistor (Q_(ref)) 125 shown in FIG. 1 is a BJT (bipolar junction transistor), those of ordinary skill in the art will appreciate from the present disclosure that other types of transistors (e.g., a metal-oxide-semiconductor field-effect transistor (MOSFET), heterojunction bipolar transistor (HBT), metal-semiconductor field-effect transistor (MESFET), gallium arsenide field-effect transistor (GaAsFET), or the like) are available for other implementations. The reference transistor (Q_(ref)) 125, along with the remainder of the bias circuit 120, is used to provide a reference current (I_(ref)) to the PA 110, which serves as an electrical bias condition that is utilized by one or more transistors included in the PA 110. To that end, the bias circuit 120 is coupled to the PA 110 through inductor (L) 118, in order to provide the reference current (I_(ref)).

The PA 110 is also coupled to receive a radio-frequency (RF) input signal (RF_(in)) from node 105 through coupling capacitor 106 (C), and provide an amplified RF output signal (RF_(out)) to an antenna through node 107. The PA 110 draws operating current from a second voltage supply line (V_(CC2)) 102 in order to receive the second voltage level V_(CC2). In some implementations, the second voltage level V_(CC2) is greater than the first voltage level V_(CC1). For example, in various implementations, the second voltage level V_(CC2) is approximately double the first voltage level V_(CC1) (e.g., V_(CC2)=5.0 V, V_(CC1)=2.2 V). For the sake of convenience and brevity, FIG. 1 includes a single amplifying transistor (Q_(PA)) 115. However, those of ordinary skill in the art will appreciate from the present disclosure that, in various implementations, a PA includes multiple amplifying transistors in various arrangements. Also, while the amplifying transistor (Q_(PA)) 115 shown in FIG. 1 is a BJT, those of ordinary skill in the art will appreciate from the present disclosure that other types of transistors (e.g., MOSFETs, HBTs, MESFETs, GaAsFETs, etc.) are available for other implementations.

As noted above, in operation, for some implementations, the PA 110 and the bias circuit 120 are switched from an off-state to an on-state on demand (and then back to the off-state), so that the PA 110 and the bias circuit 120 do not dissipate power when data is not being transmitted. Typically off-states are much longer than on-states, which allows both the amplifying transistor (Q_(PA)) 115 and the reference transistor (Q_(ref)) 125 to cool down. The amplifying transistor (Q_(PA)) 115 and the reference transistor (Q_(ref)) 125 do not necessarily cool down at the same rate, and typically heat up at different, uncorrelated rates in an on-state. As such, when switched to an on-state, the amplifying transistor (Q_(PA)) 115 and the reference transistor (Q_(ref)) 125 take time to heat up to a stable temperature, which can be as long as 200 μsec. A typical data packet, and thus the typical on-state, can be shorter than 200 μsec, while a typical off-state is often more than 10 msec. As such, in many instances, the transistors 115, 125 do not make it to a stable temperature.

In view of the power savings gained by switching between on-states and off-states, in some cases it is sufficient to accept variations in gain when the power density in the reference transistor (Q_(ref)) 125 and the power density in the amplifying transistor (Q_(PA)) 115 at least track one another. However, using previously available bias circuit technology, reliable power density tracking does not occur when the second voltage level V_(CC2) is different than the first voltage level V_(CC1).

More specifically, nonlinear changes in the respective temperatures of a reference transistor in the bias circuit 120 and an amplifying transistor 115 in the PA 110 stem from the different voltage supply levels provided to each. In turn, the power density in the amplifying transistor 115 does not track the power density in the reference transistor 125.

Typically an on-state is much shorter than the adjacent off-states. As such, transistors in both the bias circuit 120 and the PA 110 typically have to heat up to a stable temperature, which can take as long as 200 μsec. A typical data packet, and thus the typical on-state, can be shorter than 200 μsec, while a typical off-state is often more than 10 msec. As such, in many instances, the transistors in both the bias circuit 120 and the PA 110 do not make it to a stable temperature. In view of the power savings gained by switching between on-states and off-states, in some cases it is sufficient to accept variations in gain when the power density in the reference transistor in the bias circuit 120 at least tracks the power density in the amplifying transistor 115 of the PA 110. However, power density tracking is not possible when the bias circuit 120 is configured to operate using a lower supply voltage than the amplifying transistor 115 in order to reduce power consumption, according to the first approach.

The various implementations described herein include systems, methods and/or circuit-based devices provided to match a first power density in bias circuitry to a second power density in a PA, when the bias circuitry utilizes a lower voltage supply level than the PA. Numerous details are described herein in order to provide a thorough understanding of the example implementations illustrated in the accompanying drawings. However, the invention may be practiced without many of the specific details. Well-known methods, components, and circuits have not been described in exhaustive detail so as not to unnecessarily obscure more pertinent aspects of the implementations described herein.

To that end, FIG. 2 is a schematic diagram of a power amplifier (PA) operating configuration 200 in accordance with some implementations. While certain specific features are illustrated, those skilled in the art will appreciate from the present disclosure that various other features have not been illustrated for the sake of brevity and so as not to obscure more pertinent aspects of the example implementations disclosed herein. Moreover, the PA operating configuration 200 in FIG. 2 is similar to and adapted from the PA operating configuration 100 in FIG. 1. Elements common to each include common reference numbers, and only the differences between FIGS. 1 and 2 are described herein for the sake of brevity.

To that end, the PA operating configuration 200 includes a power density matching circuit 230 coupled between the bias circuit 120 and the inductor (L) 118. In turn, the inductor (L) 118 is coupled to the base of the amplifying transistor (Q_(PA)) 115 of the PA 110. The coupling capacitor (C) 106 is also coupled between input node 105 and the base of the amplifying transistor (Q_(PA)) 115 in order to provide an AC input path to the PA 110. The collector of the amplifying transistor (Q_(PA)) 115 is coupled to the second voltage supply line (V_(CC2)) 102 in order to draw DC operating current. The collector of the amplifying transistor (Q_(PA)) 115 is also coupled to node 107 in order to provide the amplified radio-frequency (RF) output signal (RF_(out)).

Those of ordinary skill in art will appreciate that in some implementations, a choke or AC blocking inductor (not shown) can be provided between the collector of the amplifying transistor (Q_(PA)) 115 and the second voltage supply line (V_(CC2)) 102. Additionally and/or alternatively, those of ordinary skill in the art will also appreciate that a DC blocking, AC coupling capacitor can be provided in series with node 107 in order to provide a substantially AC output path from the collector the amplifying transistor (Q_(PA)) 115 through node 107. With reference to the bias circuit 120, the collector of the reference transistor (Q_(ref)) 125 is coupled to the first voltage supply line (V_(CC1)) 101, and the emitter is coupled to ground.

In some implementations, the power density matching circuit 230 includes a combination of transistors provided to match power density changes between the amplifying transistor (Q_(PA)) 115 and the reference transistor (Q_(ref)) 125. In some implementations, the power density matching circuit 230 includes four transistors 231, 232, 233, 234 (Q₁, Q₂, Q₃, Q₄) arranged as follows to form a temperature independent current translator. The first and third transistors 231, 233 (Q₁, Q₃) are coupled emitter-to-collector between the second voltage supply line (V_(CC2)) 102 and ground. The collector of the first transistor 231 (Q₁) is coupled to the second voltage supply line (V_(CC2)) 102. The base of the third transistor 233 (Q₃) is coupled to the collector of the third transistor 233 (Q₃), and the emitter of the third transistor 233 (Q₃) is coupled to ground. Similarly, the second and fourth transistors 232, 234 (Q₂, Q₄) are also coupled emitter-to-collector between the second voltage supply line (V_(CC2)) 102 and ground. The collector of the second transistor 232 (Q₂) is coupled to the second voltage supply line (V_(CC2)) 102. The base of the fourth transistor 234 (Q₄) is coupled to the collector of the fourth transistor 234 (Q₄), and the emitter of the fourth transistor 234 (Q₄) is coupled to ground.

In various implementations, temperature independent current translation, and thus power density matching, is provided by sizing the four transistors 231, 232, 233, 234 (Q₁, Q₂, Q₃, Q₄) in accordance with equation (1) as follows:

$\begin{matrix} {I_{PA} = {I_{IN}\frac{E_{PA}}{E_{ref}}\sqrt{\frac{E_{2}E_{3}}{E_{1}E_{4}}}}} & (1) \end{matrix}$

With respect to equation (1), E₁, E₂, E₃, E₄ are the respective emitter areas of the four transistors 231, 232, 233, 234 (Q₁, Q₂, Q₃, Q₄). Similarly, E_(ref), E_(PA) are the respective emitter areas of the transistors 125, 115 (Q_(ref), Q_(PA)). As such, the current density (J_(PA|ref)) in the amplifying transistor (Q_(PA)) 115 relative to the reference transistor (Q_(ref)) 125 is provided by equation (2) as follows:

$\begin{matrix} {J_{{PA}|{ref}} = \sqrt{\frac{E_{2}E_{3}}{E_{1}E_{4}}}} & (2) \end{matrix}$

As an example, for J_(PA|ref)=½, E₄=4E₁=4E₂=4E₃.

FIGS. 3A-3C are schematic diagrams of different integrated circuit implementations of the power density matching circuit 230 of FIG. 2. While some example features are illustrated, those skilled in the art will appreciate from the present disclosure that various other features have not been illustrated for the sake of brevity and so as not to obscure more pertinent aspects of the example implementations disclosed herein. To that end, for example, FIG. 3A shows that in some implementations, some or all portions of the power density matching circuit 230 can be part of a semiconductor die 300. By way of an example, the power density matching circuit 230 can be formed on a substrate 302 of the die 300. A plurality of connection pads 304 can also be formed on the substrate 302 to facilitate functionalities associated with some or all portions of the power density matching circuit 230.

FIG. 3B shows that in some implementations, a semiconductor die 300 having a substrate 302 can include some or all portions of the bias circuit 120 and some or all portions of the power density matching circuit 230 of FIG. 2. A plurality of connection pads 304 can also be formed on the substrate 302 to facilitate functionalities associated with some or all portions of the bias circuit 120 and some or all portions of the power density matching circuit 230 of FIG. 2.

FIG. 3C shows that in some embodiments, a semiconductor die 300 having a substrate 302 can include some or all portions of the power amplifier (PA) 110, some or all portions of the bias circuit 110 and some or all portions of the power density matching circuit 230 of FIG. 2. A plurality of connection pads 304 can also be formed on the substrate 302 to facilitate functionalities associated with some or all portions of the PA 110, the bias circuit 120, and the power density matching circuit 230.

In some implementations, one or more features described herein can be included in a module. FIG. 4 is a schematic diagram of an implementation of a module 400 including the power density matching circuit 230 of FIG. 2. While some example features are illustrated, those skilled in the art will appreciate from the present disclosure that various other features have not been illustrated for the sake of brevity and so as not to obscure more pertinent aspects of the example implementations disclosed herein. The module 400 includes a packaging substrate 452, connection pads 456, a die 300 (e.g., a bipolar junction transistor (BJT) die), a die 410 (e.g., a heterojunction bipolar transistor (HBT) die), a matching network 412, and one or more surface mount devices (SMDs) 460.

The BJT die 300 includes a substrate 302 including some or all portions of the bias circuit 120 and some or all portions of the power density matching circuit 230 of FIG. 2. A plurality of connection pads 304 is formed on the substrate 302 to facilitate functionalities associated with some or all portions of the bias circuit 120 and some or all portions of the power density matching circuit 230 of FIG. 2. Similarly, the HBT die 410 includes a substrate 402 including some or all portions of the PA 110. The HBT die 410 also includes a plurality of connection pads 404 formed on the substrate 402 to facilitate functionalities associated with some or all portions of the PA 110.

The connection pads 456 on the packaging substrate 452 facilitate electrical connections to and from each of the BJT die 300 and the HBT die 410. For example, the connection pads 456 facilitate the use of wirebonds 454 for passing various signals and supply currents and/or voltages to each of the BJT die 300 and the HBT die 410.

In some implementations, the components mounted on the packaging substrate 452 or formed on or in the packaging substrate 452 can further include, for example, one or more surface mount devices (SMDs) (e.g., 460) and one or more matching networks (e.g., 412). In some embodiments, the packaging substrate 452 can include a laminate substrate.

In some implementations, the module 400 can also include one or more packaging structures to, for example, provide protection and facilitate easier handling of the module 400. Such a packaging structure can include an overmold formed over the packaging substrate 452 and dimensioned to substantially encapsulate the various circuits and components thereon.

It will be understood that although the module 400 is described in the context of wirebond-based electrical connections, one or more features of the present disclosure can also be implemented in other packaging configurations, including flip-chip configurations.

In some implementations, a device and/or a circuit having one or more features described herein can be included in a radio-frequency (RF) device such as a wireless device. Such a device and/or a circuit can be implemented directly in the wireless device, in a modular form as described herein, or in some combination thereof. In some embodiments, such a wireless device can include, for example, a cellular phone, a smart-phone, a hand-held wireless device with or without phone functionality, a wireless tablet, a wireless router, a wireless access point, a wireless base station, etc. That is, those skilled in the art will also appreciate from the present disclosure that in various implementations the power amplifier open loop current clamp may be included in various devices, such as a computer, a laptop computer, a tablet device, a netbook, an internet kiosk, a personal digital assistant, an optical modem, a base station, a repeater, a wireless router, a mobile phone, a smartphone, a gaming device, a computer server, or any other computing device. In various implementations, such devices include one or more processors, one or more types of memory, a display, and/or other user interface components such as a keyboard, a touch screen display, a mouse, a track-pad, a digital camera and/or any number of supplemental devices to add functionality.

FIG. 5 is a schematic diagram of an implementation of a wireless device 500 including one or more features described herein, such as the power density matching circuit 230 of FIG. 2. While some example features are illustrated, those skilled in the art will appreciate from the present disclosure that various other features have not been illustrated for the sake of brevity and so as not to obscure more pertinent aspects of the example implementations disclosed herein.

One or more power amplifier (PAs) 516 as described herein are biased by respective bias circuit(s) (not shown) and compensated by respective compensation circuit(s) (not shown). In some implementations the PAs 516 are packaged into a module, including for example an HBT die. The PAs 516 can receive respective radio-frequency (RF) signals from a transceiver 514, that can be configured and operated in known manners to generate RF signals to be amplified and transmitted, and to process received signals. The transceiver 514 is shown to interact with a baseband sub-system 510 that is configured to provide conversion between data and/or voice signals suitable for a user and RF signals suitable for the transceiver 514. The transceiver 514 is also shown to be connected to a power management component 506 that is configured to manage power for the operation of the wireless device 500. To that end, the power management module is coupled to the bias circuit 120 and the power density matching circuit 230, which are coupled between the PAs 516 and the battery 509.

The baseband sub-system 510 is shown to be connected to a user interface 502 to facilitate various input and output of voice and/or data provided to and received from the user. The baseband sub-system 510 can also be connected to a memory 504 that is configured to store data and/or instructions to facilitate the operation of the wireless device, and/or to provide storage of information for the user.

In the example wireless device 500, outputs of the PAs 516 are matched and routed to an antenna 524 via respective duplexers 150 and a band-selection switch 522. The band-selection switch 522 can include, for example, a single-pole-multiple-throw (e.g., SP4T) switch to allow selection of an operating band (e.g., Band 2). In some embodiments, each duplexer 520 can allow transmit and receive operations to be performed simultaneously using a common antenna (e.g., 524). In FIG. 5, received signals are shown to be routed to “Rx” paths (not shown) that can include, for example, one or more low-noise amplifiers (LNAs).

A number of other wireless device configurations can utilize one or more features described herein. For example, a wireless device does not need to be a multi-band device. In another example, a wireless device can include additional antennas such as diversity antenna, and additional connectivity features such as Wi-Fi, Bluetooth, and GPS.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” The word “coupled”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

The above detailed description of embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed above. While specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. For example, while processes or blocks are presented in a given order, alternative embodiments may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments.

While some implementations of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure. 

What is claimed is:
 1. A bias circuit comprising: a reference device connectable to receive a first electrical supply level, the reference device arranged to produce an electrical bias condition using the first electrical supply level, and the reference device connectable to provide the electrical bias condition to an amplifier device, the amplifier device connectable to a second electrical supply level, the second electrical supply level distinct from the first electrical supply level; and a power density matching circuit connectable between the reference device and the amplifier device, the power density matching circuit provided to substantially set a first power density associated with a first transistor included in the reference device and a second power density associated with a second transistor included in the amplifier device relative to one another, the first power density being a function of the first electrical supply level and the second power density being a function of the second electrical supply level, the power density matching circuit comprising at least one transistor with a base terminal coupled to the first electrical supply level.
 2. The bias circuit of claim 1 wherein at least one of the reference device and the amplifier device includes one of a BJT, a MOSFET, a HBT, a MESFET, and a GaAsFET.
 3. The bias circuit of claim 1 wherein the first electrical supply level is a first voltage level that is less than a second voltage level corresponding to the second electrical supply level.
 4. The bias circuit of claim 1 wherein the power density matching circuit includes a current translator circuit.
 5. The bias circuit of claim 4 wherein the current translator circuit includes a combination of transistors that are each sized relative to one another in order to set a current density in the amplifier relative to a current density in the reference device.
 6. The bias circuit of claim 4 wherein the current translator circuit includes portions of at least two current mirror arrangements of transistors.
 7. The bias circuit of claim 4 wherein the current translator circuit operation is substantially independent of temperature.
 8. A module comprising: a packaging substrate configured to receive a plurality of components; a reference device connectable to receive a first electrical supply level, the reference device arranged to produce an electrical bias condition using the first electrical supply level, and the reference device connectable to provide the electrical bias condition to an amplifier device connectable to a second electrical supply level, the amplifier device connectable to a second electrical supply level, the second electrical supply level distinct from the first electrical supply level, and at least a portion of the reference device is included on the packaging substrate; and a power density matching circuit connectable between the reference device and the amplifier device, the power density matching circuit provided to substantially set a first power density associated with a first transistor included in the reference device and a second power density associated with a second transistor included in the amplifier device relative to one another, the first power density being a function of the first electrical supply level and the second power density being a function of the second electrical supply level, the power density matching circuit comprising at least one transistor with a base terminal coupled to the first electrical supply level and at least a portion of the power density matching circuit is included on the packaging substrate.
 9. The module of claim 8 wherein at least a portion of the power density matching circuit is included on a first die.
 10. The module of claim 8 wherein the first electrical supply level is a first voltage level that is less than a second voltage level corresponding to the second electrical supply level.
 11. The module of claim 8 wherein the power density matching circuit includes a current translator circuit.
 12. The module of claim 11 wherein the current translator circuit includes a combination of transistors that are each sized relative to one another in order to set a current density in the amplifier relative to a current density in the reference device.
 13. The module of claim 11 wherein the current translator circuit includes portions of at least two current mirror arrangements of transistors.
 14. A radio-frequency (RF) device comprising: a transceiver configured to process RF signals; an antenna in communication with the transceiver configured to facilitate transmission of an amplified RF signal; a power amplifier connected to the transceiver and configured to generate the amplified RF signal; and a bias module including: a reference device connectable to receive a first electrical supply level, the reference device arranged to produce an electrical bias condition using the first electrical supply level, and the reference device connectable to provide the electrical bias condition to power amplifier connectable to a second electrical supply level, the amplifier device connectable to a second electrical supply level, the second electrical supply level distinct from the first electrical supply level; and a power density matching circuit connectable between the reference device and the power amplifier, the power density matching circuit provided to substantially set a first power density associated with a first transistor included in the reference device and a second power density associated with a second transistor included in the amplifier device relative to one another, the first power density being a function of the first electrical supply level and the second power density being a function of the second electrical supply level, the power density matching circuit comprising at least one transistor with a base terminal coupled to the first electrical supply level.
 15. The RF device of claim 14 wherein the RF device includes a wireless device.
 16. The RF device of claim 14 wherein the wireless device includes at least one of a base station, a repeater, a cellular phone, a smartphone, a computer, a laptop, a tablet computer, and peripheral device.
 17. The RF device of claim 14 wherein the power density matching circuit includes a current translator circuit.
 18. The RF device of claim 17 the current translator circuit includes a combination of transistors that are each sized relative to one another in order to set a current density in the amplifier relative to a current density in the reference device. 